A modern bowling centre has automatic pin setting apparatus for re-positioning the pins in a bowling lane after each frame is played. Such apparatus usually includes either ultrasonic or light beam scanning equipment to confirm the position of the pins after they have been re-set. Off spot location of a pin is a problem because a pin may wobble after being set up by the automatic setting device. However, the ultrasonic or light beam scanning equipment is not sensitive enough to detect that a pin is only slightly off its proper spot location and the only way to detect the displacement is to recycle the setting device. In any event the known equipment is expensive and requires skilled installation and maintenance. Furthermore the known equipment requires a mainframe computer for its operation, which makes it economical only for large centres having twelve or more lanes.
Prior patents are known which disclose devices for detecting the position of a bowling pin over a given spot. An example of such a device is seen in U.S. Pat. No. 2,014,306 issued Sept. 10, 1935 to G. D. Barker. However, the Barker device provides its own light source with a reflector on the bottom of the pin which contravenes regulations governing the bowling sport. Another detector carrying its own light source is disclosed in U.S. Pat. No. 2,346,428 to N. Hanley. A dector using a photocell is shown in Swiss Patent No. 366,228 to Rossetti dated Dec. 15, 1962. Both the Hanley device and the Rossetti device suffer from the disadvantage that any irregularity in the bottom of the pin overlying the detector will allow light to enter through the transparent cover of the dector which may activate the photocell, thus causing the device to be inaccurate.
It is an object of the present invention to provide a pin sensor, for use in a bowling centre lane, which has an improved ability to detect the off spot location of a bowling pin.